In the neurosciences, memory span is the number of items, usually words or numbers, that a person can retain and recall. Where numbers are used it is also known as digit span, and the test is called digit repetition. It can be seen as a measure of working memory (or short-term memory, depending on the psychological framework used), although other factors such as attention and comprehension also contribute to the performance on this test.

In a typical test of memory span, a list of random numbers is read out at about the rate of one per second. The test begins with two to three numbers, increasing until the person commits errors. Recognisable patterns (for example 2, 4, 6, 8) should be avoided. At the end of a sequence, the person being tested is asked to recall the items in order. The average digit span for normal adults without error is seven plus or minus two.

Reverse repetition is more difficult and requires more processes besides immediate recall.

Individuals with larger memory spans can keep in mind more different stimuli, and this seems to give them an advantage for a wide variety of cognitive tasks. Memory span has been linked to performance on intelligence tests, reading skills, problem solving, and a variety of other cognitive tasks.